The game of golf is played worldwide by a vast variety of players ranging from beginners, to novices, to world class professionals. Unlike other sports, golf requires more finesse as opposed to strength and speed. This is especially so in that part of the short game involved with the green. Typically, greens are composed of contours on a putting surface which can include fingers, knobs, rolls, decks and ridges. Their placement, width, length, height and slopes will influence the challenge and playability of putting on the green and the difficulty of maintaining the surface. For many players the most difficult part of the game to master is putting where touch and feel are the most important. Much practice plus detailed knowledge of the green are critical to success. As a result, the putting green presents a challenging playing surface wherein it is difficult for some, and impossible for others, to accurately and regularly determine the path of the ball. Part of the challenge comes from the fact that the green contours are designed to be difficult to read as they include many changes and often feature very small angles of deviation from level. Many efforts, largely unsuccessful, have been attempted to assist the golfer in mastering the art of putting and reducing “read” errors.
U.S. Pat. No. 7,610,688 (“688 Patent”) issued Nov. 3, 2009 to inventor Ji Hae Yun of Korea proposes that X and Y axis spirit levels be secured to the outsole of an atypical golf shoe. The description provides for a laterally extended sole which is then viewed by the golfer using what is described as a spirit level in an effort to determine slope of the golfing surface. The 688 Patent teaches the application of a spirit level at different frontal locations on the shoe and suggests both a rigid or a flexible spirit level.
Spirit levels, such as are disclosed in the 688 Patent, are designed to operate with a rigid tube so as to provide a reliable indication of a level condition along the length of the level. Spirit levels do not provide the actual slope. The 688 Patent is not known to this inventor to present an operable golfing device. Other references discussed in the 688 Patent include a spirit level secured to the top surface of the toe or to the inside edge of the heel of a golf shoe. These are described as ineffective.
U.S. Pat. No. 8,819,947 shows the use of a single spirit level mounted in a removable shoe cap located at the toe and on the outside surface of the shoe. In both cases this is a clip on to the body of the shoe as a whole or molded directly as part of the shoe. In these cases an elongated spirit level is shown as secured along its length to the golf shoe in those locations which are most likely to suffer from multi-axial bending and irregular wear, such as the forward or front part of the shoe. Where a lateral side of the shoe is shown the spirit level is secured along its length to a portion of the shoe where bending, torsion and wear are at their highest. This would quickly render such a spirit level or the actual shoe inoperative or worse.
Levels are remarkably difficult to read both accurately and quickly especially if the user is not using the level on a regular basis. When using a level, the bubble moves in the opposite direction of what someone inexperienced in its use may think it should travel. For example, one standing on a downward slope may assume the bubble should be at the lower end of the level, whereas the bubble is actually present in the opposite end of the level vial. This is made much more difficult when the spirit level is being read not from the side with the measured slope in the background but rather from the top down with no reference plane. The golf course itself, especially at and near the hole, is specifically designed and constructed to present a putting surface which appears to be planar and smoothly finished but which, in fact, is carefully organized to include a variety of very small deviations and changes in contour for the purpose of making the surface difficult to “read”.
Attachment of a spirit level to a golf shoe in locations such as the top or front of the toe piece are highly prone to deviation in use over the wide variety of heat, humidity and wetness conditions experienced in periods as short as a single round of golf and with wear over time. These locations offer or tend to offer an orientation which is indeterminate over short and long term ranges of time and thus are unreliable for diminishingly small angles. Further, merely securing a spirit level to a shoe is prone to failure since the shoe itself is flexible and in constant motion, all the while bending and flexing in all 3 dimensions as the user walks, bends, shifts position, kneels and stands. Golf shoes are designed with a significant lifetime over which they will be subjected to long periods of disuse followed by intensely active use in widely varying conditions. Thus, the golf shoe suffers from significant wear which is highly dependent on the usage of the individual user. Spirit levels are also reliant on air bubbles, which are unreliable as they may break into multiple bubbles or may be difficult for a user to see. The bubble can potentially break up into several smaller bubbles with the force of the foot striking the ground when walking. This problem would make it difficult to properly read the bubble. An air bubble has no colour and therefore would be difficult to see from a distance or in varying light conditions.
Some devices intended to assist a golfer to “read the green” are carried by a golfer in his pocket or golf bag and when used they are then placed on the surface of the green. The device can be as simple as a bull's eye level or as complex as an “app” that is downloaded to a cell phone. To use the cell phone or the mechanical bull's eye level they are then placed on the green at a designated area. The problem with this method is three fold.                a. Generally the device is set down in a location somewhere along the line where the golfer expects to putt. This takes time and is cumbersome to handle.        b. Because the device is placed on the green in one location it provides only a limited amount of information about the topography between the golf hole and the golf ball.        c. If a golfer was to move the device around the green to gather more information on the topography of the green it can be distracting to other players involved in the same group and unduly delay the putting progress and time spent on the green.        
Other attempts to use a gradiometer to measure a surface include the following references:                U.S. Pat. No. 3,751,819;        U.S. Pat. No. 3,812,593;        U.S. Pat. No. 5,157,842;        U.S. Pat. No. 5,209,470;        U.S. Pat. No. 5,755,623;        U.S. Pat. No. 5,820,476;        U.S. Pat. No. 6,386,994;        U.S. Pat. No. 6,408,545;        U.S. Pat. No. 6,665,962; and        U.S. Design Pat. 632,351.        
Those references do not teach an effective improvement of the short game and putting in golf.